An industry wide emphasis on sustainable asphalt practices has given rise to increasing use of warm mix asphalt technologies. WMA reduces both binder viscosity and mixing and compaction temperatures by 20-55°C during the asphalt mix production and laydown process. This research investigates several bio-derived WMA additives that act as chemical modifiers with surfactant properties. Two established additives derived from the forest products industry are studied as well as a WMA additive in development that is derived from corn. The WMA material responses are measured for binder testing and mixture testing. All binder testing with the additives was conducted using a Performance Grade (PG) 64-22 binder and the same binder was polymer modified with an SBS polymer to attain a PG 70-22 binder. Dynamic modulus testing on a State DOT approved 10 million ESAL mix design was performed to compare stiffness at a wide range of temperatures and frequencies. The newly developed, corn-derived IDB additive was successful in allowing asphalt to be compacted at a reduced temperature. All additives were added at the same dosage level. The IDB binder and mix test results were comparable to other commercially available WMA additives; however, no particular additive consistently produced the highest or lowest test results.
Available at: http://works.bepress.com/eric_cochran/22/